A big white and gray box with windows and blue accents in the middle of an industrial park’s busy highway. That is what the CyrusOne Data Center in Aurora looks like.
The Chicago Mercantile Exchange, or CME, Group Data Center next door looks similar.
But before you see the warehouse-like buildings, you might hear them first.
On a sunny day with few clouds and low wind, and after new regulation, the center was not as loud as it could be. In fact, the nearby traffic was often louder.
Mercy Davison, director of planning and zoning for the Town of Normal, and a staffer and intern took a tour of the outside of the CyrusOne facility on such a day.
“As you know, the town has a moratorium in place for data centers to give us time to study them, and I had never seen one in person. So I wanted to be sure I could see what one looked like, sounded like, etc.,” she said.
Davison said talks with City of Aurora staff and examination of their public process could provide a good guide for Normal.
“We did not go into a data center; they’re very high security, so they’re not going to invite you in, but we were able to see where are they in relation to the highway, what kind of walls did they have or what do they even look like,” said Davison.
She said it is one visit in order for her staff to better understand data centers before the town makes a decision.
“I’m still formulating opinions about it,” she said. “Really, this was a fact-finding mission, and so it was really helpful to just be able to see those centers and learn more about how they operate, and what is it that people might be experiencing. …Today set us up for additional research.”
Davison said anyone of interest or concern has the ability to find and observe them in public. Bloomington mayor Dan Brady previously told WGLT city staff have not made any official trips to visit a data center. The city passed its own six-month moratorium on any data center action in May.
The public may bring up a swath of concerns regarding data centers, but at least for those in Bloomington-Normal, not everyone has the reality to speak to. Officials from the City of Aurora have dealt with several of these concerns including job creation, energy and noise.
Are they noisy?
Aurora's 10 data centers cannot operate at a noise level exceeding 56 dB at the property line during the day and 46 dB during the evening, starting at 7 p.m. Sixty decibels is comparable to the noise of a face-to-face conversation and 40 is around the noise of a light rain.
When CyrusOne started operating its data center in April 2025, the noise was one of the first issues that landed on the desk of the new mayor, John Laesch, as residents persistently complained of the constant noise of the facilities.
“The way we approached it, both legally and legislatively, was to adopt noise limits at the property line,” he said. “So, the state of Illinois currently regulates how sound is measured through a nine-octave band measuring system, and it’s regulated by the Illinois Pollution Control Board. What we did to make it easier for people…we tried to change it to a decibel system.”
Now, the city will employ both measures of sound to address resident concerns, because the octave system was difficult to enforce alone, according to Chief Development Services Officer John Curley.
“You’re allowed to have a certain decibel within those high frequencies. The next band down, [it's] a different decibel level within that band, and so there’s variable decibel levels within all of those nine bands,” said Curley. “But it complicates things to a point where the equipment, in order to measure it, is very expensive and complex to run.”
On top of that, Curley said those in the nearby neighborhood, less than a half mile away, are trying to measure the sound themselves on decibel readers. After Aurora set its own regulations on the decibel levels measured by Curley and his staff, the city followed suit in passing it and a number of other regulations on data centers.
Difficulties surrounding the mitigation of noise levels is not simple, though. Curley said problems are still being worked out, like when air chillers are on the ground versus on a roof at the centers.
“So, we’re 50 ft in the air. ...A lot of common tools to try and mitigate visual and sound aren’t effective, because you’re too high in the air,” he said. “We don’t have any trees in the way, any trees that we planted on these sits as part of our landscape requirements for buffering aren’t going to get to 50 ft.”
So, as the sound travels in its waves, Curley said sometimes noise can exist in neighborhoods or other places as wind takes the amplitude of the wave farther.
“There’s a period of time when the sound is further away from the point source, not because it’s closer to the ground, but there is this weird phenomenon where some of the closer residents might actually experience less than somebody that’s another couple blocks away,” he said.
The complicated combination of factors is what led Aurora to adopt its decibel measurement ordinance. Curley said the mitigation is expected to be finished in August.
While there is no set time required to handle such a complaint by residents, Aurora officials said the city is working as efficiently as it can.
No louder than the corn
Roughly a mile from the nearest homes and the rest of the City of DeKalb is another data center by Facebook parent company Meta. It is the only one Meta has in Illinois.
The hyperscale facility covers former farmland and started operating in 2022.
But out among the farmland and other industrial facilities — the data center is silent. Completely silent.
This center was announced and built in DeKalb before data center issues were known by many Illinoisans, so the city council faced no opposition at the time, said City Manager Bill Nicklas.
Since then, Nicklas said the city has not had to deal with complaints about the center due to noise or any other pollution issue. He said that is because Meta worked beforehand to make the facility less noticeable and problematic for residents.
'Not on this site'
Others, like Edged, are doing the same thing to make a community-friendly project. The division of the Endeavour Energy company will build on 560 acres of land just south of Meta in a project that was approved last December.
“The ThermalWorks system is foundational to our facilities; it runs in all of our facilities and has been for years,” said Jeremy Piela, Endeavour’s director of data center design. “We’ve got a team with decades of experience behind it and the systems have just an excellent track record of operating safely and efficiently.”
Piela is referring to the company’s newest technology to avoid even more water usage at the future facility. “
“The ThermalWorks advanced waterless cooling system is the first ultra-efficient, high density platform to virtually eliminate the data center water footprint,” according to Endeavour Energy.
It is not the only new technology promised by Endeavour.
“Everyone is concerned about smelly, noisy, loud diesel generators. Well, not on this site. And the question is, ‘Why?,’” said David Morton, Microgrids director. “It’s pretty simple. ...A diesel generator has hundreds of moving parts. We have four; one of them is a fan.”
Morton said the facilities’ planned TurboCell generators will also avoid the aforementioned issues residents typically have with data centers.
While it seems like DeKalb may be setting itself up for another facility that would not significantly disrupt the everyday lives of residents, not everyone was pleased.
In the public comment period when the Edged project was approved in DeKalb, residents had mixed opinions on the data center project.
Megan Renwick spoke at the December city council meeting where the new data center was approved. She is a lifelong resident of DeKalb.
“I’m afraid that the proposed data center will contribute to 560 acres of habitat loss and light and sound pollution, both of which will disturb our natural environment along with the wildlife in it,” she said.
“That’s why, when we take a look at how much we’ve already impacted our local wildlife here in DeKalb County and take a look at the environmental harm data centers are causing, we should be doing everything in our power to protect all of the residents in DeKalb County, especially those who didn’t have a voice to be able to speak here today.”
Others at that meeting spoke positively about the prospective project. Jake Castanza did so because of the work he and the area's laborers’ union, Local 32, have been given due to the Meta Data Center’s additional revenue to the community.
“We are thankful for what the Meta Data Center has done and what we know this data center will do if accepted,” he said. “We’re thankful for the new elementary school…we’re thankful for the fire station, we’re thankful for the great road program, we’re thankful for the continued investment.”
With portions of the data center expected for completion through 2032, time will tell on whether it will be as profitable and quiet as Meta.
